Here are some citations:
Cris B. Nichols, Superintendent, Galveston, Houston & Henderson Railroad
H. Herbert Beazley; Philip F. Apel, C. S. Navy; and W. Nelson Shaw, C. S. Navy, to Commodore William W. Hunter, February 5, 1862
“Believing it to be a duty that we owe to the country and ourselves to harass and annoy as far as lies within our power the lawless and unnatural enemy who is now blockading our port, we submit to you this memorial, humbly asking your consent and assistance.
“We propose taking the little sloop Fanny Morgan, for which we shall provide the 1-pound rifle gun invented by Mr. Nichols, of this city, and, sailing out to the beacon, endeavor to draw out the luanches of the Santee, which have hitherto so readily pursued all the small craft that has appeared off our harbor, and if possible sink them.
“Should we fail in this we propose taking a few shots at the Santee, merely to try the gun, which, with an improved ball, we believe will carry 3 miles.”
ORN, 1, XVII, p. 168
Major General John B. Magruder endorsement on Major Charles M. Mason to Captain Edmund P. Turner, June 24, 1863
“Why are both the gunboats, Bayou City and Diana, at Harrisburg? What number of men, what ammunition, and what small-arms are on board, or attached to each of the gunboats? There are no long-range or heavier guns to be spared for these boats, except the Nicholl guns, which may be used for this purpose on the gunboats in Galveston Bay. Major Mason will cause this to be done without delay; suitable detachments detailed. I will see that they are well drilled at these Nicholl guns, and will report upon the same as soon as they are so drilled, reporting, in the meantime, his progress in carrying out this order.”
OR, 1, XXVI, Pt. 2, p. 82
Leon Smith, Commanding Marine Department, Velasco, Texas, to Captain Edmund P. Turner, Assistant Adjutant General, August 9, 1863
“In trying the guns upon my boats, I found the Nichols gun totally unfit for service, and turned it over to the ordnance officer at this post.”
“The trail of the 18-pounder El Dragon brass gun broke off close to the cheeks at the first fire; it was apparently perfectly sound, but on examination of the pieces after the casualty, I found it was totally unfit for service by dry rot.”
OR, 1, XXVI, Pt. 2, p. 156
“Other notes in the Richmond Examiner referring to breech-loading cannon follow:”
“September 19, 1861: ‘A new breech-loading cannon invented by Mr. Nichols, superintendent of the G. H. and H. Railroad, was tried out to-day. It is of wrought iron, four feet long, and one and a quarter inch bore, rifled. It is self-priming and takes a pound ball like a Minie ball and three ounces of powder. Extreme range at fifteen degrees was three to four miles.’” (p. 333)
Richard D. Steuart, “First in the Art of War,” Confederate Veteran, Vol. XXXV (1927)